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Category Archives: Past Diseases

While the news has continued to focus on new developments in the Zika Virus, another, more-widespread virus, is utilizing mosquitos as a mode of transmission. Malaria is caused by Plasmodium parasites, and is transmitted to humans by the Anopheles mosquito. The life cycle of Plasmodium parasites occurs in both mosquitos and humans.

Plasmodium life cycle (CDC.gov)

When the parasite is brought to humans by the mosquito, the parasite infects and begins causing symptoms. In mosquitos, the parasite lives without affecting the host in a negative way. As seen in the map below, malaria is most commonly noticed in central Africa, parts of Asia, and some countries in South America. Malaria is also seen in less frequent amounts throughout central and eastern Asia, central America, and parts of Mexico. Children, pregnant women, those who have compromised immune systems, and those who have never traveled to a region with Malaria are most at risk to contract the disease.

Distribution of malaria transmission rates throughout the world (CDC.gov)

Malaria usually presents 7-30 days after being bitten by an infected mosquito. Many times, malaria is treatable if diagnosed quickly. The primary symptoms include fever, sweats, headaches, chills, and vomiting. As the disease progresses, generally in the next 48 hours after symptoms are first observed, symptoms can worsen, including seizures, kidney failure, hypoglycemia, blood coagulation, and severe fevers. If not treated quickly, malaria can become fatal.

Fortunately, there are treatments available for those who are diagnosed with malaria, and many are effective if started quickly after diagnosis. Many drugs focus on killing the parasite that causes malaria. While these treatments exist in the United States and other developed countries however, they are not as accessible in many of the regions that are hit the hardest by malaria.

As I described in my last post, the World Health Organization has declared that the Ebola crisis has ended. I figured now would be a great time to describe a brief history of the Ebola Virus and what the scientific community is doing to protect us from the next outbreak.

The first reported cases of Ebola in humans occurred in 1976 in a remote village near the Ebola River in Zaire.

Bats are the natural animal-host of the Ebola virus, and are able to carry the virus without getting sick.

There are five versions of the Ebola virus in the wild, four of which can infect and sicken humans.

Prior to the most recent outbreak beginning in 2014, the previous largest outbreak sickened 425 people and killed 225 people. The most recent outbreak sickened over 28,000 people, and killed over 11,000.

Ebola is spread through direct contact with infected bodily fluids or medical supplies used to treat Ebola patients. There is some evidence that Ebola can also be transmitted sexually through semen, though this link is not yet solidified.

There are no treatments for Ebola, and patients who are diagnosed with Ebola are given supportive therapy to keep them alive, and allow their immune system to fight against the virus.

There are no approved vaccines for Ebola, but two trial vaccines were examined during the most recent outbreak and look promising.

If an individual has survived an Ebola infection, they are estimated to have antibodies for at least 10 years, protecting them from future infections of the same strain of Ebola.

Map detailing the sources of Ebola outbreaks, from 1976 to present (CDC.gov)